This invention relates to a method and apparatus for operating ah engine, and more particularly to an improved method and apparatus for operating an engine in response to actual conditions sensed in the combustion chamber and for determining certain operating parameters and running conditions of the engine.
With modern technology and electronics, many of the components and running conditions of an internal combustion engine can be controlled more accurately than with previous mechanical systems. For example, the control of the air/fuel ratio, spark timing, fuel injection timing and pulse, and other adjustable factors of engine operation are greatly facilitated through the use of electronic components and electronic computers. However, in order to accurately sense the running of the engine and the various phenomena occurring within the combustion chamber, it is necessary to provide a sensor that is directly positioned within the combustion chamber or in proximity to it and which senses the actual combustion conditions in the engine.
It has been understood that knocking can be determined by an optical sensor that operates within the combustion chamber and which senses the luminosity of the gases in that chamber. A wide variety of knock detectors have been proposed that employ such sensors. However, the inventors have discovered that luminosity in the combustion chamber and in particular various gain independent parameters of the luminosity signal or curve can indicate a much wider range of operating parameters and running conditions of the engine than previously realized.
It is, therefore, a principal object of this invention to provide an improved apparatus and method for operating an engine wherein a luminosity detector and particular gain independent parameters of its luminosity signal or curve are used to determine certain combustion conditions occurring in the combustion chamber such as start and end of combustion and to determine certain engine operating parameters and engine running conditions.
It is a further object of this invention to provide an improved system and method for operating an engine wherein the engine's adjustable parameters such as air/fuel ratio, spark timing, fuel injection, etc., can be varied in response to the luminosity signal and in particular various gain independent parameters of that signal so as to provide better running of the engine.
It is a still further object of this invention to provide engine control systems wherein the engine can be controlled in response to the luminosity signal. The control system should be predicated on certain measured parameters of the engine. For example, it is very desirable to be able to obtain and measure such engine parameters and running characteristics as peak cylinder pressure in relation to output shaft or crank angle, air/fuel ratio, indicated mean effective pressure (IMEP) (which is in effect the same as measuring engine torque or power), NO.sub.x emissions and the gas temperature at exhaust valve opening.
A type of engine sensor has been proposed that senses the actual luminosity of the gases within the combustion chamber. A wide variety of U.S. Pat. Nos. illustrating and describing the use of such sensors have issued including the following:
4,358,952 PA1 4,369,748 PA1 4,377,086 PA1 4,393,687 PA1 4,409,815 PA1 4,412,446 PA1 4,413,509 PA1 4,419,212 PA1 4,422,321 PA1 4,422,323 PA1 4,425,788 PA1 4,468,949 PA1 4,444,043 PA1 4,515,132
For the most part, these patents disclose arrangements wherein the sensor is utilized to sense only total luminosity and to equate the luminosity signal to a knocking signal. However, as previously noted, the inventors have discovered that this luminosity signal or curve and in particular various gain independent parameters of the luminosity signal can also be employed to determine particular phenomena occurring in the combustion chamber and to provide an indication of various engine parameters and running characteristics.